Nausea and vomiting

Question 1

Nausea

Answer 1

Unpleasant urge to vomit
Sensation
Presentation - palor, sweating

Question 2

Vomiting (emesis)

Answer 2

Forceful expulsion of stomach contents by contraction of abdominal muscles and diaphragm

Question 3

Retching

Answer 3

Reverse peristalsis of the stomach and the oesophagus without vomiting

Question 4

Vomiting centre location

Answer 4

Medulla oblongata of the brainstem

Question 5

Causes of vomiting

Answer 5

Infection - toxic materials in the gut lumen

Chemotherapy drugs

Question 6

Vomiting induction

Answer 6

Stimulus
Enterochromaffin cells in the mucosa release 5-HT
AP discharge in vagal afferents to brainstem
Co-ordination of vomiting by VC

Question 7

Events preceding vomiting

Answer 7

Hypersalivation
Sweating
Tachycardia
Nausea

Question 8

Events during vomiting

Answer 8

Intestinal slow wave activity stops
Reverse peristalsis
Suspension of breathing
Relaxation of LOS
Contraction of diaphragm and abdominal muscles
Ejection of gastric content though open UOS

Question 9

Consequences of severe vomiting

Answer 9

Dehydration 
Metabolic alkalosis 
Hypokalaemia 
Mallory weiss tear 
Aspiration

Question 10

Dopamine antagonists

• example
• use
• mechanism of action
• administration route

Answer 10

Eg: metoclopramide, domperamide
Use: Drug induced vomiting
MOA: Acts centrally by blocking CTZ
Administration: Buccal tablets, rectal suppositaries

Question 11

5HT3 receptor antagonists:

• example
• use
• mechanism of action
• side effects

Answer 11

Eg: setron
Use: chemotherapy induced N&V, post op N&V
MOA: Block peripheral and central 5-HT3 receptors
Side effects: headaches, constipation

Question 12

Histamine H1 anti-histamines

• example
• use
• mechanism of action
• side effects

Answer 12

eg: Cyclizine
Use: motion sickness, morning sickness, post op N&V
MOA: Block H1 receptors in vestibular nuclei & NTS
Side effects: CNS depression, sedation

Question 13

Anticholinergics

• eg
• use
• mechanism of action
• side effects

Answer 13

EG: hyosine
Use: motion sickness
MOA: block muscarinic receptors in VC, NTS, vestibular nuclei
Side effects: sedation, blurred vision, urinary retention, dry mouth

Question 14

Chemotherapy induced N&V additional management

Answer 14

NK1 receptor antagonist - apreniant
Corticosteroids - dexamethasone
Benzodiazepines - loraxepam, diazepam
Triple therapy is the best: HT3 receptor antagonist + corticosteroid + NK1RA